The standard eye test chart is such a recognised artefact in western culture that it has been frequently hijacked by designers to use in their products, layouts, t-shirts and prints. Designers do this, I think, as they appreciate the simplicity of the typography and the purity of the functional form of the chart. Unlike the use of a certain red cross, the overuse of the eye chart typography is not likely to find the designer the subject of a lawsuit. It could however be a design cliché worth avoiding unless you can do it well.

Some designers, however, have augmented the design in a commercially successful way, for example, this print by the Keep Calm and Carry On‘s founding duo Hayley & Lucas:

I had my eyes tested today and was introduced to two eye charts that are used for young children and illiterate people. The Lea test (according to Wikipedia) was developed by a Finnish ophthalmologist Lea Hyvärinen in 1976. It uses simple line drawings of an apple, a house, a square, and a circle rather than the usual letters. Can’t say that the apple is particularly successful.

The other test, the “Tumbling E Chart” was also developed in 1976 by Hugh Taylor and is used to test the visual acuity of illiterate people.

One interesting fact that Wikipedia has alerted me to, in regards to the standard Snellen chart, is that the letters are not a standard typeface but a specially drawn font that has equal weighting between the black lines and the white space of each letter. Only the letters C, D, E, F, L, N, O, P, T, Z are used, and the height of the letter is five times the width of the line.